wet gas compression
wet gas compression
(OP)
In a gas pipeline project I have several wet gas compressors (80-90% gas)
for these compressors preliminary spec. give a 85% polytropic efficiency,
which is the standard procedure to model these compressors ?
I can model as adiabatic (assuming 85% efficiency) but I would prefer a more accurate procedure.
for these compressors preliminary spec. give a 85% polytropic efficiency,
which is the standard procedure to model these compressors ?
I can model as adiabatic (assuming 85% efficiency) but I would prefer a more accurate procedure.





RE: wet gas compression
my copy of Prode Properties includes three methods to model compressors (rigorous polytropic cycle with selectable thermodynamic packages)
a ) Huntigton, applicable to gas phase, based on (Maxell) dH=TdS+VdP, works with a simplified model for compressibility integrated from p1 to p2, quite accurate and fast (accuracy depends from correct prediction of gas volumes)
b ) Schultz (Asme PTC 10), applicable to gas phase, based on PV ^ n = C which is exact for real gases only, Schultz includes corrections for real gases, I have read reports that this method gives higher errors than Huntington but it's a reference for industry (as GPSA method)
c) Polytropic solution with phase equilibria, based on solution of phase equilibria along a polytropic path, accurate (possibly most accurate in my tests based on entropy flash), can be very slow (compared to Huntington or Schultz), I use this method when a liquid phase is present.
I think the last procedure (Polytropic solution with phase equilibria) is what you need, it's a iterative procedure, the manual has some additional information
'http://www.prode.com/docs/pppman.pdf'
RE: wet gas compression
I have to wonder what operation uses centrifugal or axial compressors for wet gas? And when you say 80% to 90% gas what do you mean? Is the other 10-20% (by volume I'm assuming) chicken feathers, pond scum, water, or condensable hydrocarbons? 10% liquid by volume into any compressor is not going to end well. I often compress wet gas at 100% RH which ends up having 0.1% water vapor (by volume) that becomes 0.0000001% of the volume when it condenses. 10% of 1 MMSCF is 17,000 bbls of water. That is a lot of water.
David Simpson, PE
MuleShoe Engineering
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RE: wet gas compression
RE: wet gas compression
i recommend you contact the compressor mfg and forward your request to them. each mfg will utilize a method for modelling or determining the performance of the compressor. additionally, the mfg should be able to furnish you the performance curves of the compressor (especially if centrifugal compressor).
good luck!
-pmover
RE: wet gas compression
PaoloPemi,
I'll review Prode Properties and the methodology applied (not aware of that).
David,
it's a preliminary design, as you may know there are several kind of pumps/compressors allowing gas+liquid, at following stages we will define all the details
poli60,
I can model adiabatic cycle, not polytropic
pmover,
as said it's a preliminary design stage, I fully agree with you that we need to contact manufacturers to get all the details required to model the compression unit
Marie
RE: wet gas compression
for a recent project we have utilized Prode Properties,
results have been found in agreement with manufacturer's simulation,
(the problem there is the definition of the polytropic efficiency).
RE: wet gas compression